Project Summary/Abstract The American workforce is aging; by 2020, a quarter of the workforce will be over 55 years old. As sleep and circadian challenges are magnified in older adults, countermeasures for these workers, especially those working night shifts, are imperative. Night shift work leads to a mismatch between the timing of circadian rhythms and the timing of the work/sleep schedule. This in turn leads to sleepiness during nighttime work, increasing the risk of performance errors and injuries. Night shift workers also typically sleep in the morning after returning from work, thereby arising 8+ h prior to their next night shift. They thus begin work with a great amount of sleep pressure due to prolonged wakefulness, further exacerbating their sleepiness. While a number of strategies to improve sleep and alertness in shift workers have been tested, few such studies have been carried out in older adults. In the previous grant period we tested a sleep timing strategy in a lab study in older adults: scheduling sleep to begin in the early afternoon and extend into the evening, such that awakening occurs 1-2 h prior to the next night shift. We found that the older participants were able to spend 8 h in bed in the afternoon-evening, they got significantly more (and less disrupted) sleep than participants who slept ad lib, their night shift alertness and performance was increased, and they showed reduced levels of the stress hormone cortisol. We now propose to translate that laboratory-tested sleep intervention to an operational environment and evaluate its efficacy, feasibility and acceptability. In a Field Trial, we will conduct a randomized study of the 8h afternoon-evening sleep intervention in older nurses to evaluate its efficacy for improving sleep duration/quality and performance/alertness across 3 consecutive night shifts. Exploratory analyses will focus on stress, subjective fatigue, mood, and quality of life. We will also Survey a large group of older night shift workers to determine their typical sleep timing, factors influencing their sleep timing and duration following night shifts, and challenges to an 8h afternoon-evening sleep episode, to explore the feasibility of disseminating and implementing this intervention among a broad population of older night workers. To further understand how 8h afternoon-evening sleep impacts on- and off-shift activities in ?real life? and barriers to adoption of such a schedule, we will carry out Focus Groups where the feasibility and acceptability of the sleep intervention will be explored. Inadequate sleep is one of the most challenging problems affecting the 3 million older American night workers. Given our increasing understanding of how sleep deficiency contributes to adverse performance, health, safety, and quality of life, it is imperative to translate successful laboratory countermeasures and test them in operational settings. This rigorously designed study will evaluate such a countermeasure and test its efficacy, feasibility and acceptability in older nightshift workers.